CN114985684B - Design method of metal mold low-pressure casting pouring system with overflow slag ladle - Google Patents
Design method of metal mold low-pressure casting pouring system with overflow slag ladle Download PDFInfo
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- CN114985684B CN114985684B CN202210918746.5A CN202210918746A CN114985684B CN 114985684 B CN114985684 B CN 114985684B CN 202210918746 A CN202210918746 A CN 202210918746A CN 114985684 B CN114985684 B CN 114985684B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/08—Features with respect to supply of molten metal, e.g. ingates, circular gates, skim gates
- B22C9/082—Sprues, pouring cups
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D18/00—Pressure casting; Vacuum casting
- B22D18/04—Low pressure casting, i.e. making use of pressures up to a few bars to fill the mould
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Abstract
The invention belongs to the technical field of low-pressure casting, and particularly discloses a design method of a metal type low-pressure casting gating system with an overflow slag ladle, which comprises the steps of preliminarily determining the position of the slag ladle according to a flow state result in a mold flow analysis and the design of a parting line of a casting; designing the thickness of a slag ladle neck and the size of a slag ladle according to the temperature result in the mold flow analysis and the wall thickness characteristic of a casting; according to the particle tracking result in the mold flow analysis, the specific shape of the slag ladle and the position of the exhaust plug in the slag ladle are optimized, the method is particularly suitable for large-scale complex thin-wall aluminum alloy castings such as large-scale aluminum alloy hollow integral auxiliary frames, battery boxes, motor shells and the like which are formed by metal mold low-pressure casting, and the entrainment gas generated in the metal mold aluminum alloy low-pressure casting and filling process and the oxide and the cold charge at the front end of molten metal are discharged into the slag ladle, so that the undercasting risk and the content of oxidized slag inclusion at the intersection position of the molten metal filling tail end and the molten metal in the castings are obviously reduced, and the quality and the qualification rate of the complex thin-wall large-scale castings are improved.
Description
Technical Field
The invention belongs to the technical field of low-pressure casting, and particularly relates to a design method of a metal mold low-pressure casting pouring system with an overflow slag ladle, in particular to a pouring system obtained by designing the overflow slag ladle in the pouring system according to the structural characteristics of a casting and combining the analysis result of casting mold flow, designing and optimally designing the position of the slag ladle, the size and the shape of the slag ladle and the position of an exhaust plug.
Background
Under the dual promotion of energy-saving and emission-reducing pressure and new energy automobile performance improvement demands, the automobile lightweight process is accelerating, wherein the automobile chassis lightweight is new blue sea, the permeability of aluminum alloy battery packs, auxiliary frames, control arms, steering knuckles and the like is continuously improved, and more thin-wall castings, hollow castings and high-integration aluminum alloy large-size castings are pushed to the market.
The lightweight design of large-size castings generally has the following characteristics: 1) the integrated structure of a plurality of parts is changed into an integral casting structure, the size is large, the shape is complex, and the technical requirements of different parts of the casting are obviously different; 2) further reducing the wall thickness of the casting, and designing according to the minimum limit thickness of the forming process; 3) in order to improve the lightweight effect, the casting is designed into a hollow structure.
CN114653924A discloses a low-pressure casting and pouring system for a feeding path of a complex thin-walled part, which adopts a mode of combining a T-shaped cross gate, a bottom pouring type sprue, a side pouring type sprue, a column type ingate and a gap type ingate to solve the problems of complex geometric shape, thinner wall thickness, large longitudinal height difference, easy shrinkage porosity and shrinkage cavity generation, poor mechanical property and the like in the casting process of an L-shaped aluminum alloy casting. CN105033223A discloses a gating system for low-pressure casting of a metal aluminum ring, which comprises a sprue, a cross gate, an inner gate and the like, wherein a plurality of convex bodies are uniformly distributed on the outer side wall of a sand core in the area of each casting mold cavity in an annular manner. And the production cost is saved by one module. However, the above low-pressure casting pouring system is not suitable for the low-pressure casting preparation of large-size complex thin-wall light-weight castings. The structural characteristics of large-size complex thin-wall lightweight castings cause the dispersion of casting hot spots of the castings, and a plurality of gates are required to be arranged to feed the hot spots, so that great challenges are brought to the mold filling process of traditional low-pressure casting, and molten metal can generate more front-end cold materials, oxidized inclusions and entrainment gas due to long flow path and complex flow field in the mold filling process, and the quality of the castings is seriously affected.
At present, a filter screen is usually arranged at the top of a lift pipe before entering a casting cavity to reduce oxides and inclusions in molten metal, but the filter screen has no effect on entrainment and secondary oxidation slag inclusion formed after the molten metal passes through the filter screen. The traditional metal type low-pressure casting process forming mode cannot meet the production of large-size complex thin-wall aluminum alloy castings such as high-performance hollow integral auxiliary frames, battery packs and the like.
To reduce the problems caused by front-section cold charge, oxide inclusion and gas entrainment, when a casting and pouring system is designed, a mode of designing a slag collecting bag and an exhaust groove at the first impact, junction or last forming part of molten metal is often adopted to avoid the problems. However, the design of the casting process of the large-size parts such as the actual hollow integral auxiliary frame, the battery pack and the like is mainly judged by the experience of workers, the improvement and optimization are realized by a trial and error mode, the efficiency is low, the period is long, the cost is high, and an effective and reasonable process design method is lacked.
Disclosure of Invention
In order to solve the technical problems, the invention provides a design method of a metal mold low-pressure casting gating system with an overflow slag ladle, so that the entrainment and secondary oxidation slag inclusion in the mold filling process of low-pressure casting large-scale complex castings are eliminated or reduced, and the quality of the castings is improved. The invention is particularly suitable for large-scale complex thin-wall aluminum alloy castings such as large-scale aluminum alloy hollow integral auxiliary frames, battery boxes, motor shells and the like which are formed by metal mold low-pressure casting.
In order to achieve the purpose, the complete technical scheme of the invention comprises the following steps:
a design method of a metal mold low-pressure casting pouring system with an overflow slag ladle comprises the following steps;
step 1: performing mould flow analysis on the low-pressure casting process scheme of the hollow integral auxiliary frame, performing mould filling by using three lift pipes from two sides and the center of the integral auxiliary frame, wherein the mould flow calculation comprises casting mould filling and particle tracking, and aluminum liquid enters a mould through the lift pipes in the mould filling process and fills the auxiliary frame body;
step 2: according to the result of mold filling flow and particle tracking in the mold flow analysis result, two sides of the middle position of the front beam of the auxiliary frame are respectively provided with an overflow slag ladle;
and step 3: after the position of a slag ladle is selected, a parting line is moved to the upper part of a casting, the parting line is modified from a straight shape to a slope shape, and a first shape characteristic of a flow guide effect is designed on the casting, wherein the first shape characteristic is a rhombic flow guide groove arranged on the surface of the casting;
and 4, step 4: designing the width, thickness and length of the slag ladle neck, wherein the radius of a fillet at the long edge of the junction of the slag ladle neck and the casting is 1.3 times of the thickness of the slag ladle neck, and the radius of the fillet at the junction of the slag ladle neck and the slag ladle is 5.2 times of the thickness of the slag ladle neck;
and 5: designing the shape of the slag ladle into a 8 shape formed by double cylinders along the flowing direction of the molten metal, and guiding the molten metal to form two vortexes in the slag ladle;
step 6: and (4) performing mold flow analysis again on the process scheme added with the slag ladle, and determining that the casting is qualified if the air contact time of the casting part is less than 0.3s, the molten metal enters the slag ladle to form vortex, the air pressure in the slag ladle is less than 1100mbar, and no region with the temperature of the front end of the molten metal being 15 ℃ lower than the alloy liquidus line exists before the molten metal enters the slag ladle.
And if the temperature of the front end of the molten metal is in a region which is 15 ℃ lower than the alloy liquidus line in the slag ladle neck, increasing the thickness of the slag ladle neck, correspondingly modifying the fillet radius of the long edge of the boundary of the slag ladle neck and the casting and the fillet radius of the boundary of the slag ladle neck and the slag ladle, and performing mold flow analysis on the modified scheme again until all indexes meet the requirements.
In the step 1, the casting material is cast aluminum A356 alloy, the pouring temperature is 720 ℃, the mold temperature is 350 ℃, the liquid-lifting rate is set to be 20mbar/s, and the liquid-lifting rate in the cavity is set to be 8 mbar/s.
In the step 4, the width of the slag ladle neck is designed to be 40 mm; the thickness of the slag ladle neck is 2 mm; the length is 15 mm.
The included angle between the two sides of the rhombic diversion trench of the overflow slag ladle is 32 degrees and 148 degrees respectively, and the depth of the diversion trench is as follows: side length =1: 3.7.
The diameter of a single circle of the 8-shaped overflow slag ladle is phi 45mm, the distance between two circles is 50mm, the thickness of the overflow slag ladle is 24mm, the slope of the side surface of the overflow slag ladle is 12 degrees, the total volume of the overflow slag ladle is 68.3cm for cultivating a tree, a phi 12 ejector rod is arranged in the middle of the 8-shaped overflow slag ladle, and a phi 12 exhaust plug is respectively arranged at the center of a vortex position formed by molten metal in the slag ladle.
A design method of an overflow slag ladle of a metal type aluminum alloy low-pressure casting pouring system comprises the following steps;
step 1: performing mold flow analysis on the split auxiliary frame low-pressure casting process scheme, performing mold filling from a central lift pipe of the split auxiliary frame, wherein the mold flow calculation comprises casting mold filling and particle tracking, and aluminum liquid enters a mold through the lift pipe in the mold filling process and is filled in an auxiliary frame body;
and 2, step: according to the mold filling flow and particle tracking results in the mold flow analysis results, two sides of a welding area of the mold filling tail end of the split type aluminum alloy auxiliary frame casting are respectively provided with an overflow slag ladle;
and step 3: designing a position parting line of a slag ladle on the upper part of a casting, and designing a second shape characteristic with a flow guiding effect on the casting, wherein the second shape characteristic is a notch positioned between two overflow slag ladles, and the notch comprises an arc-shaped section positioned in front of the center and used for shunting and curve sections which are respectively connected with the arc-shaped section at two sides of the arc-shaped section and used for buffering;
and 4, step 4: designing the width, thickness and length of a slag ladle neck, wherein the radius of a fillet at the long edge of the junction of the slag ladle neck and a casting is 1.6 times of the thickness of the slag ladle neck, and the radius of the fillet at the junction of the slag ladle neck and the slag ladle is 4.2 times of the thickness of the slag ladle neck;
and 5: designing the shape of the slag ladle into a 9 shape along the flowing direction of the molten metal, and guiding the molten metal to form a vortex in the slag ladle;
step 6: and (4) performing mold flow analysis again on the process scheme added with the slag ladle, and determining that the casting is qualified if the air contact time of the casting part is less than 0.3s, the molten metal enters the slag ladle to form vortex, the air pressure in the slag ladle is less than 1100mbar, and no region with the temperature of the front end of the molten metal being 15 ℃ lower than the alloy liquidus line exists before the molten metal enters the slag ladle.
In the step 1, the casting material is cast aluminum A356 alloy, the pouring temperature is 715 ℃, the mold temperature is 350 ℃, the liquid-lifting rate is set to be 20mbar/s, and the liquid-lifting rate in the cavity is set to be 8 mbar/s.
In the step 4, the width of the slag ladle neck is designed to be 20 mm; the thickness of the slag ladle neck is 2 mm; the length is 15 mm.
The overflow slag ladle of the metal type aluminum alloy low-pressure casting pouring system is characterized in that the diameter of a circle of a 9-shaped overflow slag ladle is phi 38mm, the thickness of the overflow slag ladle is 19mm, the slope of the side surface of the overflow slag ladle is 20 degrees, the total volume of the overflow slag ladle is 14.9cm for carrying out heavy planting, and a phi 12 exhaust plug is respectively arranged at the center of a vortex position formed by molten metal in the slag ladle.
Compared with the prior art, the invention has the advantages that:
1) the method has the advantages that the influence of the entrainment gas and the secondary oxidation slag inclusion on the performance of the casting in low-pressure casting is eliminated or reduced, the effects on the complex casting with long flow path and variable flow state and the thin-wall casting with high performance requirement are particularly remarkable, the method is particularly suitable for large-scale complex thin-wall aluminum alloy castings such as large-size aluminum alloy hollow integral auxiliary frames, battery boxes, motor shells and the like which are formed by metal mold low-pressure casting, the undercasting risk of the molten metal filling tail end and the molten metal intersection position and the content of the oxidation slag inclusion in the casting are remarkably reduced, and the quality and the qualification rate of the complex thin-wall large-size casting are improved.
2) Providing the designed size and shape reference of the overflow slag ladle in the pouring system, shortening the process design time and reducing the subsequent iterative verification time of the overflow slag ladle effect;
3) and establishing a specific result criterion by using mold flow analysis and actual experience to evaluate the overflow slag ladle effect of the pouring system before formal mold opening.
Compared with the prior art, the method can effectively guide technicians in the field to synchronously design effective overflow slag ladles in the development process of the aluminum alloy low-pressure casting large complex parts so as to eliminate or reduce the air entrainment and secondary oxidation slag inclusion of the aluminum alloy low-pressure casting large complex thin-wall parts, improve the quality and performance of castings, shorten the development period and improve the product percent of pass. Has great economic and social value.
Drawings
FIG. 1 is a schematic view of the structure of an integrated aluminum alloy subframe used in example 1 of the present invention.
FIG. 2 is a graph showing the results of particle tracking in the modular flow analysis of example 1.
FIG. 3 is a schematic view of a parting line structure of an overflow slag ladle in example 1.
FIG. 4 is a top plan view of the overflow slag ladle of example 1.
Fig. 5 is a front view of fig. 4.
FIG. 6 is a schematic structural view of a split aluminum alloy subframe used in embodiment 2 of the present invention.
Figure 7 is a top view of the overflow slag ladle of example 2.
In the figure: 1-lift pipe, 2-integral auxiliary frame body, 3-auxiliary frame front beam, 4-overflow slag ladle, 5-parting line, 6-first shape characteristic and 7-second shape characteristic.
Detailed Description
The technical solutions of the present invention will be described in further detail below with reference to the drawings of the present invention, and it should be understood that the described embodiments are merely illustrative and are not intended to limit the present application.
Example 1
The invention is applied to the design of a multi-sprue low-pressure casting integral aluminum alloy auxiliary frame casting pouring system, and the overflow slag ladle is designed to collect the entrainment gas generated by the intersection of multiple strands of molten metal and the secondary oxidation slag inclusion at the front end of the molten metal, so that the casting quality is improved.
In the present embodiment and the drawings, unless otherwise specified, the symbols used represent the following: w: width of slag ladle neck, T: slag ladle neck thickness, L: slag ladle neck length, α: draft, R1: boundary of the slag ladle neck and the slag ladle of the slag ladle and the slag ladle neck, R2: boundary edge between short edge of slag ladle neck and casting, R3: the slag ladle neck and the slag ladle are intersected.
As shown in fig. 1, the integrated subframe of the present invention includes a lift tube 1, an integrated subframe body 2, a slag ladle, etc. for low-pressure casting.
Step 1: performing mold flow analysis on the low-pressure casting process scheme of the integral auxiliary frame, wherein in the analysis process, a casting material is selected to be cast aluminum A356 alloy, the initial casting temperature is selected to be 720 ℃, the initial mold temperature is selected to be 350 ℃, and three lift tubes 1 in total are designed to be filled from the two sides and the center of the integral auxiliary frame, as shown in figure 1; the liquid lifting speed is set to be 20mbar/s, and the liquid lifting speed in the die cavity is set to be 8 mbar/s. The mold flow calculation comprises casting mold filling and particle tracking, and aluminum liquid enters the mold through a liquid lifting pipe in the mold filling process and is filled in the integral auxiliary frame body 2.
Step 2: as shown in fig. 2, according to the result of mold filling flow and particle tracking in the result of mold flow analysis, it is determined that there is a condition of two molten metal intersection turbulent flows in the middle of the front beam 3 of the subframe, and two overflow slag ladles 4 are initially selected to be respectively arranged on two sides of the position to collect molten metal front end cold charge, turbulent air entrainment and secondary oxides.
And step 3: after the position of the slag ladle is selected, a parting line 5 is moved to the upper part of the casting, the parting line 5 is modified from a straight shape to a slope shape, and the slag ladle is designed to be positioned at the position where final mold filling is finished so as to achieve the effects of slag collection and overflow. And a first shape feature 6 for flow guidance is designed on the casting to increase the tendency of metal flow into the overflow ladle. In this embodiment, the first shape feature 6 is a rhombic guiding groove formed on the surface of the casting, the included angle between two sides of the rhombic guiding groove is 32 ° and 148 ° respectively, the depth of the guiding groove is determined according to the flowing condition, and the depth of the guiding groove is selected by design: side length =1: 3.7.
And 4, step 4: designing the width and thickness of a slag ladle neck: designing the width of a slag ladle neck to be 40mm according to the range of molten metal turbulence of a particle tracking track in the mold flow analysis; the thickness of the slag ladle neck is designed according to the thinnest 2mm preliminarily for facilitating subsequent removal; in order to avoid the influence of the heat of the slag ladle on the solidification sequence of the casting, the design is preliminarily carried out according to the longest 15 mm.
Designing the shape of the junction of the slag ladle neck and the casting: as shown in fig. 5, the ladle neck to casting interface long edge fillet R1 was designed to be 1.3 × ladle neck thickness = 2.6. According to the particle tracking flow direction in the primary mold flow analysis, the boundary fillet R2 between the short edge of the slag ladle and the casting is designed to be 10, so that the particle tracking track smoothly enters the slag ladle, and vortexes and cavities are prevented from being generated in the casting and the neck of the slag ladle. The slag ladle neck to slag ladle interface fillet R3 was designed to be 5.2 × slag ladle neck thickness = 10.4.
And 5: the slag ladle is positioned at the intersection position of two strands of molten aluminum, the shape of the slag ladle is designed into a shape of a '8' formed by double cylinders according to the flowing direction of molten metal, the molten metal is guided to form two vortexes in the slag ladle, and as shown in figure 4, a phi 12 exhaust plug is respectively arranged at the centers of the two vortexes. The diameter of a single 8-shaped circle of the slag ladle is designed to be phi 45mm, the center distance between the two circles is designed to be 50mm, the thickness of the slag ladle is designed to be 24mm, the inclination of the side surface of the slag ladle is designed to be 12 degrees, the total volume of the slag ladle is 68.3cm, and a phi 12 ejector rod is arranged in the middle of the 8-shaped center to facilitate demoulding of the slag ladle.
Step 6: and performing mold flow analysis again on the process scheme added with the slag ladle. The analysis result is checked to find that: the air contact time of the casting part is less than 0.3s, which indicates that the oxide at the front end of the molten metal is effectively discharged into a slag ladle in the mold filling process. The flowing state result shows that the molten metal represented by the particle tracking track smoothly enters the slag ladle to form a vortex. The air pressure result shows that the air pressure in the slag ladle is less than 1100mbar, and the exhaust plug in the slag ladle has good exhaust effect. The mold filling temperature, however, indicates that the molten metal front temperature is in the region 592 ℃ in the ladle neck, about 20 ℃ below the liquidus of the a356 alloy, with the risk of under-casting.
In order to improve the risk of insufficient casting, the thickness of the slag ladle neck is thickened to 3mm, and the fillet R1 of the long boundary edge corresponding to the slag ladle neck and the casting is changed into 3 and the fillet R2 of the slag ladle neck and the slag ladle is changed into 10.8 due to the change of the thickness of the slag ladle neck. And performing modular flow analysis on the 3D digital model of the modified scheme again to find that all indexes meet the requirements.
The integral aluminum alloy auxiliary frame casting front cross beam in the embodiment 1 has good internal quality, and meets the 0-2 level regulation in the standard of ASTM E155-2015 ray reference film for detecting aluminum castings and magnesium castings in the technical casting requirements. After T6 heat treatment, tensile strength, yield strength and elongation of the product are respectively 310MPa, 240MPa and 10.9% by adopting a tensile testing machine, and the technical requirements of the product are met. The auxiliary frame assembly passes the bench fatigue test and is verified to be qualified.
Example 2
The invention is applied to the design of a casting system of a low-pressure casting split type aluminum alloy auxiliary frame casting, and the overflow slag ladle is designed to collect the entrainment gas at the tail end of the filling mold and the secondary oxidation slag inclusion at the front end of the molten metal, so that the casting quality is improved. In the case, the filling type tail end is a welding area of the auxiliary frame casting and the extruded aluminum section, and in order to ensure the strength of a welding seam and avoid bubbling and blackening of the welding seam, the requirement on the internal quality of the area is extremely high.
As shown in fig. 6, a schematic view of the split subframe low-pressure casting of the invention specifically includes:
step 1: and carrying out mold flow analysis on the split auxiliary frame low-pressure casting process scheme, wherein in the analysis process, a casting material is selected to be cast aluminum A356 alloy, the initial pouring temperature is selected to be 715 ℃, the initial mold temperature is selected to be 350 ℃, the liquid lifting rate in the liquid lifting pipe 1 is set to be 20mbar/s, and the liquid lifting rate in a cavity is set to be 8 mbar/s. Mold flow calculations include casting filling and particle tracking.
Step 2: according to mold filling flow and particle tracking results in mold flow analysis results, molten metal turbulence and oxide gathering exist in a welding area at the mold filling tail end of the split type aluminum alloy subframe casting, and two overflow slag ladles 4 are selected to be arranged on two sides of the position respectively to collect molten metal front-end cold materials, turbulent air entrainment and secondary oxides.
And step 3: the position parting line of the slag ladle is designed on the upper part of the casting, a second shape characteristic 7 with a flow guiding function is designed on the casting, and the tendency of metal liquid flowing into an overflow slag ladle is increased, as shown in fig. 7, in the embodiment, the second shape characteristic 7 is a notch positioned between two overflow slag ladles 4, and the notch comprises an arc-shaped section positioned in the front of the center and used for flow distribution and a curve section which is respectively connected with the arc-shaped section at the two sides of the arc-shaped section and used for buffering.
And 4, step 4: designing the width and thickness of the slag ladle neck: designing the width of the slag ladle neck to be 20mm according to the range of molten metal turbulence of a particle tracking track in the mold flow analysis; the thickness of the slag ladle neck is designed according to the thinnest 2mm for facilitating subsequent removal; in order to avoid the influence of the heat of the slag ladle on the solidification sequence of the casting, the design is preliminarily carried out according to the longest 15 mm.
Designing the shape of the junction of the slag ladle neck and the casting: and 3.2 percent of the thickness of the slag-ladle neck, wherein the fillet R1 of the long edge of the boundary of the slag-ladle neck and the casting is 1.6. According to the particle tracking flow direction in the primary mold flow analysis, the boundary fillet R2 between the short edge of the slag ladle and the casting is designed to be 15, so that the particle tracking track smoothly enters the slag ladle, and vortexes and cavities are prevented from being generated in the casting and the neck of the slag ladle.
Designing the shape of the junction of the slag ladle neck and the slag ladle: fillet R3 at 4.2 × slag neck thickness = 8.4.
And 5: the slag ladle is positioned at the tail end of the mold filling, the shape of the slag ladle is designed into a shape of 9 along the flowing direction of the molten metal, the molten metal is guided to form a vortex in the slag ladle, and a phi 12 exhaust plug is arranged at the center of the vortex. The diameter of the '9' -shaped round of the slag ladle is designed to be phi 38mm, the thickness of the slag ladle is designed to be 19mm, the inclination of the side surface of the slag ladle is designed to be 20 degrees, and the total volume of the slag ladle is obtained by carrying out high-speed and high-speed downward slope cultivation on 14.9 cm.
Step 6: and performing mold flow analysis again on the process scheme with the slag ladle added. The analysis result is checked to find that: the mold filling temperature shows that the front end of the molten metal does not have a region 15 ℃ lower than the liquidus line of the A356 alloy, and the risk of insufficient casting caused by too low temperature does not exist. The oxide results show that the air contact time of the casting part is less than 0.3s, which indicates that the oxide at the front end of the molten metal is effectively discharged into a slag ladle in the mold filling process. The flowing state result shows that the molten metal represented by the particle tracking track smoothly enters the slag ladle to form a vortex. The air pressure results show that the air pressure in the slag ladle is less than 1100mbar, and the exhaust plug in the slag ladle plays a good exhaust effect.
The split type aluminum alloy auxiliary frame casting welding area is good in internal quality, and meets the 0-1 level regulation in the standard of ASTM E155-2015X-ray reference plate for detecting aluminum castings and magnesium castings in the technical casting requirements. After T6 heat treatment, a tensile testing machine is adopted to test that the tensile strength, the yield strength and the elongation of the aluminum alloy auxiliary frame casting respectively reach 300MPa, 230MPa and 11.3 percent. The appearance of the casting and the section is in a fish scale pattern after the casting and the section are connected through inert gas shielded welding, and the phenomena of air bubbles and blackening do not occur. The tensile strength, yield strength and elongation of the cast iron reach 220MPa, 178MPa and 7.9 percent respectively by adopting a tensile testing machine, are higher than 60 percent of the performance of the cast iron body, and meet the technical requirements of products. The auxiliary frame assembly passes the bench fatigue test and is verified to be qualified.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, changes and equivalent structural changes made to the above embodiment according to the technical spirit of the present invention still fall within the protection scope of the technical solution of the present invention.
Claims (10)
1. A design method of a metal mold low-pressure casting pouring system with an overflow slag ladle is characterized by comprising the following steps:
step 1: performing mold flow analysis on the low-pressure casting process scheme of the hollow integral auxiliary frame, performing mold filling from three lift pipes on two sides and the center of the integral auxiliary frame, wherein the mold flow calculation comprises casting mold filling and particle tracking, and aluminum liquid enters a mold through the lift pipes in the mold filling process and is filled in the auxiliary frame body;
step 2: according to the result of mold filling flow and particle tracking in the mold flow analysis result, two sides of the middle position of the front beam of the auxiliary frame are respectively provided with an overflow slag ladle;
and step 3: after the position of a slag ladle is selected, moving a parting line to the upper part of a casting, modifying the parting line from a straight shape into a slope shape, and designing a first shape characteristic of a flow guide effect on the casting, wherein the first shape characteristic is a rhombic flow guide groove arranged on the surface of the casting;
and 4, step 4: designing the width, thickness and length of the slag ladle neck, wherein the radius of a fillet at the long edge of the junction of the slag ladle neck and the casting is 1.3 times of the thickness of the slag ladle neck, and the radius of the fillet at the junction of the slag ladle neck and the slag ladle is 5.2 times of the thickness of the slag ladle neck;
and 5: designing the shape of the slag ladle into a 8 shape formed by double cylinders along the flowing direction of the molten metal, and guiding the molten metal to form two vortexes in the slag ladle;
step 6: and (4) performing mold flow analysis again on the process scheme added with the slag ladle, and determining that the casting is qualified if the air contact time of the casting part is less than 0.3s, the molten metal enters the slag ladle to form vortex, the air pressure in the slag ladle is less than 1100mbar, and no region with the temperature of the front end of the molten metal being 15 ℃ lower than the alloy liquidus line exists before the molten metal enters the slag ladle.
2. The design method of the metal mold low-pressure casting pouring system with the overflow slag ladle according to claim 1 is characterized in that if the temperature of the front end of molten metal is 15 ℃ lower than that of an alloy liquid phase line in a slag ladle neck, the thickness of the slag ladle neck is increased, the fillet radius of the long edge of the boundary of the slag ladle neck and a casting and the fillet radius of the boundary of the slag ladle neck and the slag ladle are correspondingly modified, and the modified scheme is subjected to mold flow analysis again until all indexes meet the requirements.
3. The design method of the metal mold low-pressure casting pouring system with the overflowing slag ladle according to claim 1, wherein in the step 1, the casting material is cast aluminum A356 alloy, the pouring temperature is 720 ℃, the mold temperature is 350 ℃, the liquid-raising rate is set to be 20mbar/s, and the liquid-raising rate in the cavity is set to be 8 mbar/s.
4. The design method of the metal mold low-pressure casting pouring system with the overflowing slag ladle as claimed in claim 1, wherein in the step 4, the width of the slag ladle neck is designed to be 40 mm; the thickness of the slag ladle neck is 2 mm; the length is 15 mm.
5. The metal mold low-pressure casting pouring system with the overflow slag ladle designed according to the method of any one of claims 1 to 4, is characterized in that the included angles between two sides of the rhombic diversion trench of the overflow slag ladle are respectively 32 degrees and 148 degrees, and the depth of the diversion trench is as follows: side length =1: 3.7.
6. The low pressure metal casting gating system with the overflow slag ladle as claimed in claim 5, wherein the diameter of a single circle of the "8" -shaped overflow slag ladle is phi 45mm, the distance between the two circles is 50mm, the thickness of the overflow slag ladle is 24mm, the slope of the side surface of the overflow slag ladle is 12 degrees, the total volume of the overflow slag ladle is 68.3cm for cultivating, a phi 12 ejector rod is arranged in the middle of the "8" -shaped overflow slag ladle, and a phi 12 vent plug is respectively arranged at the center of the vortex position formed by the molten metal in the slag ladle.
7. A design method of a metal mold low-pressure casting pouring system with an overflow slag ladle is characterized by comprising the following steps:
step 1: performing mold flow analysis on the split auxiliary frame low-pressure casting process scheme, performing mold filling from a central lift pipe of the split auxiliary frame, wherein the mold flow calculation comprises casting mold filling and particle tracking, and aluminum liquid enters a mold through the lift pipe in the mold filling process and is filled in an auxiliary frame body;
step 2: according to the mold filling flow and particle tracking results in the mold flow analysis results, two sides of a welding area of the mold filling tail end of the split type aluminum alloy auxiliary frame casting are respectively provided with an overflow slag ladle;
and step 3: designing a position parting line of a slag ladle on the upper part of a casting, and designing a second shape characteristic with a flow guiding effect on the casting, wherein the second shape characteristic is a notch positioned between two overflow slag ladles, and the notch comprises an arc-shaped section positioned in front of the center and used for shunting and curve sections which are respectively connected with the arc-shaped section at two sides of the arc-shaped section and used for buffering;
and 4, step 4: designing the width, thickness and length of a slag ladle neck, wherein the radius of a fillet at the long edge of the junction of the slag ladle neck and a casting is 1.6 times of the thickness of the slag ladle neck, and the radius of the fillet at the junction of the slag ladle neck and the slag ladle is 4.2 times of the thickness of the slag ladle neck;
and 5: designing the shape of the slag ladle into a 9 shape along the flowing direction of the molten metal, and guiding the molten metal to form a vortex in the slag ladle;
step 6: and (4) performing mold flow analysis again on the process scheme after the slag ladle is added, and determining that the casting is qualified if the air contact time of the casting part is less than 0.3s, the molten metal enters the slag ladle to form vortex, the air pressure in the slag ladle is less than 1100mbar, and no region with the temperature of the front end of the molten metal being 15 ℃ lower than the alloy liquidus line exists before the molten metal enters the slag ladle.
8. The design method of the metal mold low-pressure casting pouring system with the overflowing slag ladle according to claim 7, wherein in the step 1, the casting material is cast aluminum A356 alloy, the pouring temperature is 715 ℃, the mold temperature is 350 ℃, the liquid-raising rate is set to be 20mbar/s, and the liquid-raising rate in the cavity is set to be 8 mbar/s.
9. The method for designing a low pressure metal casting gating system with an overflow slag ladle as set forth in claim 8, wherein in step 4, the neck width of the slag ladle is designed to be 20 mm; the thickness of the slag ladle neck is 2 mm; the length is 15 mm.
10. The low-pressure metal mold casting and pouring system with the overflow slag ladle obtained by the method according to any one of claims 7 to 9, is characterized in that the diameter of the circle of the 9-shaped overflow slag ladle is phi 38mm, the thickness of the overflow slag ladle is 19mm, the side slope of the overflow slag ladle is 20 degrees, the total volume of the overflow slag ladle is 14.9cm, and a phi 12 exhaust plug is respectively arranged at the center of a vortex position formed by molten metal in the slag ladle.
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